It is common practice to seal a driver's license, a student identification card, a hospital identification card, or other similar document between two layers of transparent plastic for purposes of preservation and prevention of alteration. The transparent plastic material most frequently used for this purpose is a sheet material formed in two layers; the first layer is an outer surface film of hard, tough, smooth abrasion-resistant resin and the second is an inner surface layer or coating of a softer thermoplastic resin functioning as an adhesive. Usually, the outer surface layer constitutes a thermoset, biaxially oriented polyester resin and the inner adhesive layer is polyethylene.
A common technique for sealing an identification card into transparent plastic, using a two layer plastic sheet of the kind described, starts with the cutting of a two-panel blank or pouch from the sheet plastic. The two panels of the blank pouch are matched in size and are joined together along one edge by a fold line. It is customary to score or cut the fold line, to a depth less than the total thickness of the plastic sheet, to facilitate folding. The identification card is placed on the adhesive surface of one panel, the other panel is folded over the card, and the resulting assembly is passed through a laminating press. The press applies heat and pressure to the assembly to activate the polyethylene or other adhesive, sealing the two plastic panels to the identification card and to each other, completely encapsulating the card in the sheet plastic. The result is an essentially permanent plastic covering for the identification card that is sealed to preserve the card and to prevent alteration of the card.
In some applications, as in the case of a hospital identification card or an identification card employed for a high security situation, it is desirable to have a temporary or variable identification card associated with a permanent identification card. The requirements for protection of the permanent identification card may be at least as exacting as in the case of a driver's license or other ID card as previously described. For the temporary identification card, it is usually desirable to provide essentially similar protection except that provision must be made for replacement of the variable identification card when required. Thus, in these applications the protective transparent plastic material, in finished form, should provide complete sealed encapsulation of the permanent identification card in a pouch that also affords a receptacle into which the variable ID card may be inserted and in which it is effectively protected.